Cost of second-most common heat source in Lehigh Valley hovers around historic high.

And to think that earlier in the winter, things were looking up for people who heat their homes with oil.

For the first time in years, home heating oil prices hadn't gone up. As a matter of fact, many dealers were selling oil for less — about a dime or so — than they had been a year earlier.

But that was before January's record cold snap and an onslaught of snow storms conspired to drive up demand and constrict supply.

"This ongoing cold spell has caught a lot of us by surprise," said Mike Harned, president of Harned Durham Oil Co. and Oil Discounters in Upper Milford Township.

Tony Malandra, owner of Yeager's Fuel in Allentown, said low inventory is apparent among wholesale suppliers such as pipeline operator Buckeye Partners, which has a tank farm straddling Lower Macungie and Upper Milford townships.

"We're texting the vendors every day, asking, 'Do you have fuel?' " he said.

Some days, they don't. A variety of factors are at play.

The first, of course, is the persistent, extreme cold, which has increased demand not only for oil, but for all heating fuels, including propane and natural gas.

Propane has become so scarce this winter, suppliers have had to resort to rationing. Last month AmeriGas Propane, the country's biggest supplier, whose footprint extends to the Lehigh Valley, began limiting customers to no more than 60 percent of their tank's capacity.

Access to natural gas, too, has at times been limited by distribution problems, leading to price spikes and talk of rolling blackouts. In part because the electric grid relies so heavily on natural gas-fired power plants, grid operators have had to call on the public to reduce its energy consumption.

Meanwhile, Malandra said, some industrial consumers with the ability to switch from natural gas to heating oil have done so, leaving residential suppliers such as Yeager's scrambling to find the fuel their customers so desperately need.

Before Christmas, the price of heating oil in the Lehigh Valley was about $3.50 a gallon, give or take 25 cents or so, depending on the dealer and the particulars of a contract. More recently, the price has hovered around the $4 mark — though in recent days it has come down a bit.

"That's about as high as we've ever been," Malandra said. "There is a huge premium on these prices because there is a legitimate supply issue. It's not bogus speculation."

Heating oil remains a common heat source in the Lehigh Valley despite the rising popularity of natural gas. In Lehigh and Northampton counties, 78,536 homes relied on natural gas in 2010, according to U.S. Census estimates. Oil was a close second, heating 77,668 homes, and electric was third, in 74,405 homes.

A decade earlier, oil was the leading heat source — and by a wide margin. In 2000, 84,351 homes in the Valley used oil, compared with 60,427 that used natural gas.

The only good news for heating oil customers is that those who signed up for pre-pay plans back in the summer or fall, when prices were much lower, are now reaping the rewards.

For everyone else, the only hope is that warmer weather is around the corner. Francis Staffieri of Salisbury Township said his oil tank is down to its last eighth but he'll hold off a little longer before ordering a fill-up.

"I'm hoping the weather breaks and the prices drop," he said.

Staffieri, a 71-year-old retiree who lives on a fixed budget, said he shops around for heating fuel, calling a dozen suppliers in search of the lowest price. Nonetheless, the cost of heating fuel, like taxes, just keeps going up, he said.